This invention pertains to triaxial fabric of specific constructions more readily conformable to a shaped surface and more readily weavable. More particularly, this invention pertains to triaxial fabric constructions particularly adapted to the incorporation of high modulus fibers therein.
Stable, pliable triaxial fabrics of various weave patterns and with various properties are disclosed and claimed in U.S. Re. Pat. No. 28,155--Dow (of common assignment herewith). Variants of such fabrics more suitable for use as substrates or reinforcement in molded products are disclosed and claimed in U.S. Pat. No. 3,874,422--Dow (also of common assignment herewith). The weaves of the -422 patent are adapted for use as substrate or reinforcement applications by virtue of their better conformability or drapability about curved and complex surfaces. This property arises primarily from the incorporation in the weaves of the -422 patent of yarn courses not fully secured within the weave against transverse movement by interlocking intersections with other yarn courses. The weaves of the -422 patent are also of uniform and controlled compliancy and porosity.
A difficulty encountered with weaves of the -422 patent, however, is that these weaves are not readily adapted to be formed or woven on practical triaxial fabric-forming machinery known to date. While there has been a need for such fabrics and weaves, conformable triaxial weaves, suitable for use as molded product reinforcement or substrate applications and readily weavable on known machines have heretofore been unknown.
A somewhat separate problem is the continuing and progressive need for ever stronger and ever lighter composite molded materials including high strength reinforcements. High modulus fibers, such as graphite fiber, are an ideal material for such reinforcement. There is, therefore, a very significant need for practical woven constructions or weaves of substrate materials, adapted to include high strength, high modulus fibers such as graphite fiber, which weaves or constructions are also particularly adapted to conform to curved or complex surfaces for forming complex molded products. Most importantly, there is a need for such weaves which are more practical than those heretofore available by virtue of the fact that they may be formed on a known type of triaxial fabric-forming machinery.
It is the general object of the present invention to provide fabrics and weave constructions which may satisfy all of the foregoing needs.